The article discusses the estimation of the minimum particle count (N) required to achieve a certain level of uncertainty (UN) in particle size and shape measurements using Transmission Electron Microscopy (TEM). The authors present a method to estimate N as a function of UN and particle size distribution (PSD) using experimental TEM data. The results show that the minimum particle count needed to achieve a certain level of uncertainty (UN) decreases as the PSD becomes narrower. The authors also demonstrate that the minimum particle count is higher for materials with broader PSDs and higher polydispersity. The results can be used to improve international guidelines and standards for particle size and shape measurements, and can contribute to the implementation of legislation requiring precise measurement of characteristic values of particle size and shape distributions. The authors also discuss the limitations of TEM in characterizing materials with strong diffraction contrast and highlight the potential benefits of alternative techniques such as annular dark-field scanning transmission electron microscopy (ADF-STEM).
Evaluating nanoparticle concentration through electron microscopy to inform regulatory frameworks
